Only about 1.7 percent of Danes had Covid-19 antibodies back in April

“Estimation of SARS-CoV-2 infection fatality rate by real-time antibody screening of blood donors” (medRxiv; thanks, Colin!) describes testing donated blood in Denmark (nearly 10,000 samples) and finding that only 1.7 percent were positive for coronavirus antibodies. The blood had been donated April 6-17.

Does this mean that, now that the Danes are emerging from their bunkers, they will essentially start all over with a coronaplague? If 98 percent of the population has no immunity to plague, how is that different than if 100 percent of the population has no immunity (presumably, the situation back in December/January)? If it wasn’t safe for people to mix back in mid-March, now that 2 percent of the population is presumed immune, it is suddenly safe?

What do we make of this seemingly crazy low number for a purportedly exponentially growing disease that had at least two months to run free in Denmark? Here are some possibilities:

  • Except in certain high-density cities, coronaplague is not very contagious, nowhere near as ferocious as we were told
  • A lot of people simply aren’t susceptible to coronaplague, just as a lot of people won’t catch a cold that is going around, and, having never been truly infected, don’t develop antibodies
  • The antibody tests that we have are not reliable for determining if someone has previously been infected with coronaplague

[Another aspect of the paper that I suspect won’t interest anyone:

Using available data on fatalities and population numbers a combined IFR in patients younger than 70 is estimated at 82 per 100,000 (CI: 59-154) infections.

In other words, a person under 70 who actually does get infected with this evil virus has a 0.082% of dying (about the same as the annual risk of death from commuting via motorcycle 4,000 miles per year). Given the current popular mood, however, I think any number larger than 0% will be a sufficient justification for cowering in a bunker.]

Some other studies in the most plague-ridden areas have found 20-30 percent of the adult population with antibodies. That too, however, suggests to me that a lot of people are somehow naturally immune.

Readers: Could Denmark have truly missed this first wave of plague?


8 thoughts on “Only about 1.7 percent of Danes had Covid-19 antibodies back in April

  1. > Given the current popular mood, however, I think any number larger than 0% will be a sufficient justification for cowering in a bunker.

    It depends on how the comparison is made. 82 per 100,000 puts the death rate a little more than 1/2 the rate for dying of cancer in the United States (148/100,000 in 2018). That would make it the third leading cause of death here (I know, apples/oranges but bear with me). So if you said:

    “COVID-19 is as lethal as stroke, alzheimer’s disease and diabetes combined, and more than five times as deadly as influenza or pneumonia. And it’s more than half as deadly as dying of cancer.” I think yeah, you bet, people are going to cower. It would have to drop a long way to get to “influenza/pneumonia” and I think that’s how people would judge that comparison.

    How do they know that the blood donors are really representative of the larger population since they self-select for being healthy? In the United States I’ve heard anecdotally that blood donations are way down because people are avoiding it. If they’re testing donations from voluntary donors I don’t know how valid that is for the rest of the population, even if they’re widely distributed geographically.

    So maybe the fourth bullet point:

    People who choose to donate blood during the pandemic self-select as healthier than others, possibly skewing the antibody-positive rate downward in that group.

    I mean, here in the US, the Red Cross says:
    “Healthy donors are encouraged to book an appointment.”–covid-19–and-blood-donation.html

    • That can’t be right. 82 deaths per 100k infections can’t be equated with the generalised risk of death from a particular cause (ie you’d need to compare it with the risk of dying from cancer etc per cancer patient). Of course, that wouldn’t stop the media and the army of Facebook Karens from portraying it that way…

    • @Colin:

      One thing I forgot to note: We get around 14 deaths/100,000 for Influenza/Pneumonia in the U.S. but we have vaccines for influenza. We also try very hard to make sure that our elderly population get vaccinated, and it’s not perfect, but many of them are protected. I know in my town, for example, that the senior center offered free vaccines to everyone, as did pharmacies like Walgreens. I got mine in November 2019 at my local pharmacy in 10 minutes. So nobody had any real excuse unless they were hopeless shutins or resolute anti-vaxxers.

      We do not have a vaccine for SARS-Cov2 as of yet, so this virus hit the elderly with preexisting conditions with absolutely no immunity and no vaccine to slow it down. It should be no surprise, in that light, that the death rate is higher as a result. It may also be a little more innately dangerous to them, because of its natural characteristics, but if we stopped vaccinating the elderly and vulnerable for influenza every year, the death rate would skyrocket.

  2. “Could Denmark have truly missed this first wave of plague?”

    As of today, per, Denmark’s death rate per 1M population is 94, which is 24th highest among the 215 countries listed. The U.S.’s rate is 270, 13th highest. Total cases per 1M: Denmark, 1,875, 40th; U.S., 4,536, 12th.

    • Regardless of what the death rate might have been, if antibody positive test rate = exposure rate then it is fair to say that 98 percent of people in Denmark “missed this first wave”. That doesn’t seem plausible given what we’ve been told about how contagious this virus is.

  3. Even New York City, which as far as I know is the area hit the hardest so far by coronavirus, closed all the schools, bars, and restaurants (among other businesses) for two months. Sure, some people went out and spread the virus anyway (two of my coworkers in NYC got sick after violating the social distancing guidelines and meeting up with friends; one specifically described a person with coronavirus infecting everyone else while blowing out a birthday cake; I heard another story about a clandestine barbershop operating out of a basement which infected a bunch of people), but I don’t think you can really draw conclusions about the percentage of the population that’s naturally immune based on the antibody data. If I haven’t gotten infected yet because I didn’t have any friends over and wear an N95 mask every time I go outside, am I “naturally immune”?

    Commuting via a motorcycle is a notoriously dangerous thing that the vast majority of people refuse to do (even in California, where it lets you split lanes to avoid traffic). Let’s say you value your life at $10 million; then something that gives you a 0.082% risk of dying essentially costs you $8,200. Now say you want to see Dolittle in IMAX but you think there’s a 1% chance of getting infected if you wear your mask the whole time. Now on top of whatever you’re paying for the ticket and also concessions that will eventually give you heart disease and diabetes, there’s an implicit $82 cost for the coronavirus risk. How many movie theaters would be able to stay in business if the government enacted an $82 tax on every ticket sold?

Comments are closed.